Space discharge oscillating relay



L. M. POTTS SPACE DISCHARGE OSCILLATING RELAY June 15, 1943.-

Filed Sept. 18. 1939 FIG.1

T INVENTOR. LOUIS M. POTTS ORNEY.

Patented June 15, 1943 SPACE DISCHARGE OSCILLATING RELAY Louis M. Potts, Evaluton, Ill., auignor to Teletype Corporation, Chicago, Ill., a corporation of Delaware Application September 18, 1939, Serial No. 295,414

16 Claims.

This invention pertains to telegraph systems and particularly to such systems in which space discharge devices are embodied as parts thereof in the functions of transmitters, receivers, and relays.

The main object is to provide methods and apparatus for the operation of telegraph circuits with current of low value transmitted over the lines.

Another object is to provide methods and apparatus for the control of telegraph apparatus by the potential of the line.

Another object is to provide methods and apparatus for accomplishing these objects with a minimum number of thermionic tubes.

A feature of the invention is the provision of a system of telegraph transmission between two stations in which the transmitting, relaying, and receiving control is performed exclusively by space discharge devices.

The above objects are attained by connecting the plate of a space discharge gas filled tube in a telegraph line circuit for transmission and then supplying the grid of the tube with signal impulses for control of transmission, by connecting such a tube to the line conductor of a telegraph system and by connecting a mechanical telegraph recorder in series with the plate of such a tube at a receiving and recording telegraph station.

A more complete understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawing in which,

Fig. 1 illustrates a receiving space discharge relay in combination with a telegraph receiver magnet controlled thereby;

Fig. 2 illustrates a complete two-way transmission system using space discharge relays;

Fig. 3 illustrates a receiving relay having novel features of adjustment and control; and

Fig. 4 illustrates a receiving space discharge I relay in combination with a polarized magnet controlled thereby.

The telegraph system illustrated in Fig. 1 comprises a repeater assembly connected by transmission conductors to a transmitting substation and to a receiving recorder respectively, all equipment at the repeater being of space discharge nature without mechanical contacts.

Signal generating and amplifying apparatus at each station and signal receiving and amplifying apparatus at each station are all of space discharge nature. The amplified signals are applied to an electrically biased electromagnet for purpose of recording. All signals are single current.

. In the system illustrated in Fig. 3, the repeater is capable of control to emit either polar signals or single current signals according to its condition of adjustment, and in either case .in response to polar signal control.

In the system illustrated in Fig. 4, polar signals are received by a relay and polar signals are retransmitted.

I Referring to Fig. 1, a space discharge gas filled tube I in the relay assembly 2 has its grid 3 connected to a telegraph line conductor 4 which extends to a remote telegraph transmitter 5 at a station 6, the transmitter 5 supplying positive or negative current to the line conductor 4 and through the resistor 'I to ground and thereby supplying positive or negative potential to the grid 3 in the form of telegraph signals. The resistance I connected from the line to ground is greater in value than the series resistance of the line 4, thus providing current of low value on the line conductor 4.

The tube I comprises also a hot cathode 9 and a plate anode III. A plate battery ii is connected from ground to the plate ll, and a resistor i2 is connected from the cathode 8 to ground, to complete a plate circuit. A condenser I3 is connected between the cathode and the anode to render the tube circuits oscillatory and to place the tube circuits under control of grid 3. A conductor I4 is connected in parallel with the grounded resistor l2, the conductor extending through a telegraph selector magnet l5 of a recorder to ground to complete a transmission circuit. The recorder may be according to U. S. Patent No. 1,904,164 granted to S. Mortonet al.,

-' and is symbolized herein by a showing of the selector magnet 9, Fig. 4 of the S. Morton et a1. patent. The selector magnet in Fig. 1 and in the remaining figures will be assumed to be illustrated with its armature attracted.

In operation, movement of the middle contact member of the transmitter 5 at substation 6 to eil'ect application to the line conductor 4 of a signal of positive potential at substation 6 as shown will bias the grid 3 to render the tube i conducting. Condenser I3, charged by battery ii beginning immediately after each extinction of the discharge in the tube, now will be discharged in a negligible time interval through charges.

electrodes of the tube I. reducing potential at terminals of condenser l2 and shunting from the tube I substantially all current from battery II, the battery current being limited by Joint resistance of resistor l2 and transmission circuit l4, l in parallel, and flowing through condenser II for an appreciable time to recharge the condenser. Stray current which may flow at this time over line 4 from control grid 5 is of a neg.- ligible amount. when the condenser's terminal potential rises to the ignition point of tube l, the cycle is completed and the condenser again dis- Oscillation' of the circuit of tube l and of condenser l5 continues throughout the continuance of the signal, or as long as the line conductor 4 remains connected to positive battery at substation 5.

During oscillation of circuits of tube i, current flows from grounded battery ll through condenser IS in process of recharging, conductor I4 and electromagnet i5 to ground.

The described. current flows through the conductor i 4 and through the electromagnet II in substantially contiguous impulses, and forms a substantially uniform continuous or direct current through magnet l5. 7

Upon reversal of the contactual conditions of transmitter 5, thus connecting the line conductor 4 through transmitter 5 to negative battery, a negative signal is propagated in line 4, biasing grid 2 to render circuits of tube l nonoscillating. Condenser I! then recharges in full and remains in charged condition, terminating the described current which effected a signal in the conductor l4 and in the electromagnet l5.

Thus, polar signals are received by potential only at the'relay 2 from the substation 5 and are retransmitted by relay 2 to the selector magnet I5 wholly by space discharge means in relay 2 and without the operation of any mechanical contact in the relay.

The telegraph system illustrated in Fig. 2 comprises a plurality of identical stations of which I9, 20, and 2| are shown connected by a single transmission conductor 22. Transmission apparatus at station 20 consists of a relay tube 23 whose electrical connections are identical with those of tube I, Fig. 1, the output circuit being line conductor 22 in parallel with resistor 24, thence through resistors l1 and it in parallel to ground. The transmitting apparatus at each station is connected to the line conductor 22 through a filter designated 45 at station 20 and 44 at station 2| provided to suppress the oscillations at the transmitting stations from the line conductor. Means for supplying a polar signal to grid 25 comprises a photoelectric cell 25 and resistor 21, both having adjustable contacts on a potentiometer 25. By proper adjustment of the contacts, a higher current through the photoelectric cell 25 caused by an illuminative control (not shown) may produce a positive potential on grid 25 and a lower current through the cell 25 may produce a negative potential on grid 25, Control of the photoelectric cells may be as disclosed in United States Patent No. 2,177,077,

granted Oct. 24, 1939, to L. M. Potts. Similar arrangements are provided for tube 25 at station 2| and for a similar tube at station l5. Resistance of each resistor l1, l5, and 24 is high compared with resistance of line 22, and line currents are of low intensity.

A signal impressed upon line conductor 22 is effective upon grids of tubes as 20 and II at all stations. Each grid is provided with electrical I connections similar to those of tube I, Fig. i.

The plate circuit for tube 5i includes battery 32. resistor 54. upper or operating windings of an electrically biased selector magnet 55, plate 24'. cathode 21 and grounded resistor which is connected to a battery 25 for biasing the tube 3|. A biasing circuit for selector magnet 55 includes battery 25, resistor 45, and a biasing winding of the magnet 25. Current from tube 5| balances out the biasing magnetic field.

For operation of the structure oil-lg. 2, contacts of potentiometer 28 are adjusted to render grid 25 negative when cell 25 is dark and positive when cell 25 is illuminated. Dark photo cells and negative potentials on grids of the tubes 22 and 25 estop oscillation of circuits of tubes 25 and 25, the circuit of the latter tube being a duplicate of tube 22. Line conductor 22 attains ground potential through resistor 24 and others. Adjustment of resistor 35 and battery 25 is such that ground potential on line conductor 22 estops oscillation of tubes 35 and Si. There is, therefore, no current in the operating windings of magnets 35 and 4| and currents in the biasing windings cause the armatures of those magnets to occupy their nonoperating position. This is the normal condition of the system when not transmitting electrical signaling impulses. I

When transmitting an electrical signal impulse on line 22, illumination on the photoelectric cell 25 produces a positive potential on grid line 22 also operates tube 35 to produce a home record.

In the structure illustrated in Fig. 3 a gas filled tube 55 comprises cathode 5i, anode 52 and grid 53. Current for the plate circuit and for the output or retransmission circuit is supplied from batteries 54 and 55 through a potentiometer resistor 56 having an adjustable contact 51 connected to the anode 52 and a further adjustable contact 55 connected to an output or line circuit 59. The cathode is connected to ground and a condenser is connected from cathode to anode. The output circuit 58 includes a signal responsive device or telegraph receiver 6i which may be either polar or neutral in construction. Telegraphic signals according to two-current practice are supplied in nature of biasing potentials to grid 53 from substation 52 over line conductor 63. Output signal currents may be according to practice of polar signaling or single current signaling. Operation of the system in response to a signal of positive potential maintained .on line conductor 53, as shown at substation 62, will effect a positive biasing of grid 53 permitting the tube 55 to oscillate, producing two substantially conaaanoia ground. During the described period of current contact 51 is substantially at ground potential, and resultantly there is manifested 'at contact 88 a negative potential produced from battery 55 by virtue of the described second current. There results a third current in a path including contact 58, conductor 59 and signal responsive device 8l to ground.

' In response to change to a signal oi. negative nature at substation 82, the grid 58 becomes biased negatively. thus increasing the ignition point of the plate circuit of the tube 58 to a value above the potential 01' the contact 51. Condenser 88 then recharges but does not discharge and oscillation oi the tube 58 ceases. Current flows from negative battery at substation 82 through line conductor 88 and resistor 84 to maintain a negative biasing condition on grid 58. Current flows also in potentiometer resistor 58 from batteries M and 58, producing a ground potential at or about the middle point of the resistor 58. As shown in the drawing, contact 58 is adjusted to the described point oi ground potential and no current flows in line conductor 88 during continuance of the negative signal on line 88.

with contact 58 adjusted as shown at the point of ground potential in the resistor 58, received signals are polar and retransmitted signals are single current.

Presume now that the contact 58 has been shifted and is adjusted to a point above the middle point on the resistor 58 and indicated as 85 on the resistor 56. During a positive signaling condition on line 83, with contactor 51 substantially at ground potential, the contactor 58 now in position at 65 receives a negative potential from battery 55, and during a negative signaling condition on line 83 with the middle point of resistor 58 substantially at ground potential, the contactor 58 receives a positive potential from battery 54. Accordingly, in response to signals of positive and negative polarity respectively received from line conductor 83, the repeating equipments of Fig. 3 will retransmit signals of negative and positive polarity, respectively. Thus, polar signals are received and polar signals are retransmitted.

It has been described in detail above that with contact 58 adjusted as shown there will be retransmitted single current marking and spacing signals of current and no-current characteristics, respectively. During receipt of a positive signal, the ground potential will be located near the contact 51. It will be obvious that when contact 58 is adjusted to the point of the ground potential during receipt of a positive signal there will result a transmission of single current signals of no-current and current characteristics, respectively, thus eifecting reversal of the characteristics of the two classes of signals by readjustment of the relay devices.

By varying the position of contact 51 on the resistor 58, potential impressed on anode 52 may be varied and a desirable potential may be attained.

For any position of adjustment of contact 51, there is a corresponding first position on resistor 58 at which ground potential is manifested during receipt of a signal of positive nature, a corresponding second position on resistor 58 at which ground potential is manifested during receipt of a signal of negative nature, and a corresponding third position on resistor 58 at which a potential of one polarity is manifested during receipt of a signal of marking nature and a potential or similar voltage but of reversed polarity is manifested during receipt or a signal oi. spacing nature. Contact 88 may be adjusted to any one of these three critical points, or near them, according to the characteristics desired in the retransmitted signals in the output conductor.

Fig. 4 illustrates a system in which the principles shown in Fig. 1 are duplicated and are arranged in opposing manner to produce polar repeated signals.

At relay assembly 18 there are provided two gas filled tubes H, 12, two line resistors 18, 14, two condensers 15, 18, a battery 11, and a retransmitting resistor 18 divided into two parts 18, 88. Line conductors 8|, 82 connect the apparatus of repeating station [8 to transmitter 83 in substation 84 and through contacts or the transmitter the line conductors are connected variably to positive and negative grounded batteries 85, 88, as shown. Conductors'8l, 88 connect the apparatus of the relay assembl to signal responsive device 88.

By reason of the construction of transmitter 88 there will be connected at all times a positive signal over one of the line conductors to one of the tubes and a negative signal over the other line conductor to the other ofthe tubes. Resultantly, according to principles traversed in description oi Fig. 1, one or the other of the tubes will be oscillating, and the conductor junction 9| or 82 of the oscillating tube will be substantially grounded through the condenser of the oscillating tube circuits, while the remaining conductor junction will not be grounded.

In operation, presuming that the transmitter 83 in the condition shown represents a marking signal, positive battery 85 is connected over line 8! to grid of tube 1| wherein the circuits are oscillating and junction Si is substantially grounded, while negative battery 88 is connected over line 82 to grid of tube 12 which is accordingly biased against oscillation. Resultantly, a charging current .fiows through battery 11, resistor part 19, and condenser I5 while current flows as a retransmitted signal through battery ll, resistor part 80, line conductor 88, upward through signal responsive device 89, line conductor 81 and condenser 15, constituting a polar signal of marking nature in the device 89. Upon reversal of the contactual condition of transmitter 83, battery 85 is connected over line conductor 82 to grid of tube 12, permitting oscil lation of the circuits thereof, while battery 86 is connected over line conductor 8| to grid of tube 7|, estopping oscillation. thus substantially grounding the junction 92 and rendering the junction 9| ungrounded. Resultantly, a charging current flows through resistor part 88, while current flows as a retransmitted signal through battery 11, resistor part 19, line conductor 87, downwardly through signal responsive device 88, line conductor 88, and condenser 18, constituting a reversed polar signal of spacing nature in the device 88.

While the invention has been illustrated as embodied in several specific structures, it will be understood that it is not limited by any specific structure but may be embodied in other structures in identical or in modified form.

' What is claimed is:

1. In a telegraph system, a repeating station apparatus comprising a combination of a gas filled triode tube, batteries, a condenser, an input conductor, an output conductor, a resistor, and

means between said resistor and said tube for varying the locations of critical potential points on said resistor, and means between said resistor and said output conductor for adjusting said output conductor into electrical connection with any one of said critical potential points.

2. In a telegraph-system, a gas filled tube, batteries, a condenser, a resistor, an output con ductor, said tube comprising cathode, anode and grid, means to impress on said grid signals of marking and spacing character, connection means for manifesting on said resistor a ground potential at one point in response to impressment of a marking signal on said grid and at another point in response to impressment of a spacing signal on said grid, and means to connect said output conductor either to said one point or to said other point.

3. In a telegraph system, a gas filled tube, batteries, a condenser, a resistor, means for impressing On said tube received signals of marking and spacing nature, meansincluding conductive connections for generating on said resistor critical potentials at diiferent points on the resistor, and take-off means for delivering repeated signals of polar or of single current nature.

resistor, said condenser, and said battery, an

oscillatory circuit including said cathode, anode and condenser, and means to impress signal impulses on said grid effective under certain operating conditions to discharge said condense-r through said tube to initiate oscillations in said oscillatory circuit which oscillations continue provided the grid remains positive, and effective under other conditions to facilitate the charging of said condenser when said tube is rendered nonconductive.

5. In a telegraph transmission system, a telegraph station, a remotetelegraph station, a triode gas filled tube having cathode, anode and grid, at said first-mentioned station, a battery connected from said anode .to ground and a resistor connected from said cathode to ground forming a. plate circuit for said tube, a condenser connected directly from said cathode to said anode, means to impress received signals in the form of variable polar potentials on said grid, at retransmission circuit connected directly to said resistor and extending to said remote station, and a signal receiving device comprising a gas filled triode tube having cathode, anode and grid, at said remote station, said last mentioned grid connected directly to said retransmission circuit at said remote station.

6. In a telegraph system, two triode gas filled tubes, condensers individual to said tubes, a battery and a resistor common to said tubes, means including a telegraph transmitter and direct connections to said tubes for applying polar signals to said tubes, means including direct circuit connections for substantially grounding one end or the other of said resistor in response to operation of one or the other of said tubes, said battery connectedto a mean point of said resistor, and a signal responsive device connected between the two terminals of said resistor and grounded on one terminal or the other as one or the other 01' said tubes is operated.

7. In a telegraph system, a plurality of stations, a line circuit passing through all the stations, a resistance connected from the line to ground at each station to maintain the line at substantially ground potential with no battery potentials'applied at any station, a grid controlled thermionic tube at each station having its grid connected to the line, a condenser connected between the oathode and anode of said tube to forms. relaxation oscillator therewith wherein the'oscillations continue at the same amplitude provided positive potential is impressed on said line, a recorder controlling magnet connected in the plate circuit of the tube at each station, and transmitting means associated with each grid circuit to change its potential for controlling the flow of the plate current in each tube only during the oscillation of said relaxation oscillator to operate its associated magnet.

8. As in 7 in which the resistances connected from the line to ground are much greater in value than the series resistance of the line whereby the potential for controlling the grid is uniform at all stations.

. 9. In a telegraph system, a recorder controlling magnet having two windings one of which normally carries no current, means to continuously supply current to the other winding to hold the v armature of the magnet, a telegraph line, said line connected to the grid to initiate oscillation in the alternating current path and alter the flow of the current in the direct current path when the transmitter raises the grid voltage above a critical value, said oscillations being eflective to return the flow of the direct current to its first stage when the transmitter reduces the grid voltage below the critical value, the line circuit being connected at such a point in the direct current path that current flows in one direction for one condition and in the other direction for the other condition.

1:. In a telegraph system, a telegraph circuit, terminal stations associated with the circuit, an intermediate station associated with the circuit, a resistance greater than the resistance of the circuit connecting two sides of the circuit at at least one of the stations, all portions of said circuit being maintained conductive for both positive and negative signaling conditions, means to change the potential between the two sides of the circuit at any station, a grid controlled thermionic tube at each station having its grid connected to said said circuit, an electromagnet in a local circuit at v each station. and means to control the now or tion of said relaxation oscillatorsolely by the change of potential on the line.

12. In a telegraph system, a telegraph circuit, a thermionic tube having a cathode, a grid and a plate, the telegraph circuit being included in-a direct current path associated with the plate, an oscillating circuit including a capacitor associated with the plate, means to initiate oscillations in the oscillating circuit by changes in the grid potential, and means to maintain direct current in the telegraph circuit by the charging current for the capacitor and means to interrupt the line current by the discharge current.

13. As in 12, and an electrical nlter between the oscillating circuit and the line to block the leakage of the alternating current to the line.

14. In a telegraph system, a transmitter, a receiver, and a repeater, said repeater including a gas tube having a cathode, anode, a grid. an oscillatory circuit in said repeater including the cathode, anode, and a condenser. a circuit for charging said condenser, a line conductor connecting said transmitter to said grid for impressing Sinai impulses on the grid to cause the oscillatory circuit to oscillate, which oscillations continue at the same amplitude provided the grid remains positive, and a signaling circuit including said receiver in parallel with the condenser charging circuit whereby current is supplied to said receiver during said oscillation of said oscillatory circuit.

15. In a telegraph system, a plurality oi stations connected by a single transmission conductor, signal generating apparatus at each station including space discharge gas iilled tubes, all or said apparatus being of space discharge nature, high terminal impedances at each station, whereby the current cn the line is of minimum value, means for connecting the grids of the receiving station space discharge gas filled tubes directly to the transmission line, whereby said tubes are controlled solely by the potential of the line, and electrically biased electromagnetic recording devices at said receiving stations controlled by said space discharge tubes to eflect recording operations in accordance with the signal impulses impressed on the transmission line.

16. In a telegraph system, a triode "gas filled tube having cathode, anode, and grid, a battery connected from said anode to ground and a resistor connected from said cathode to ground forming a plate circuit, a condenser connected directly from said cathode to said anode, a charging circuit for said condenser comprising said resistor, said condenser, and said battery, an oscillatory circuit including said cathode, anode, and condenser, means to'impress signal impulses on said grid eflective under certain operative conditions to discharge said condenser through said tube to initiate oscillations in said oscillatory circuit which oscillations continue at the same amplitude provided the grid remains positive, and

cuit. I

more M. Po'rrs. 

